Examples of lighting apparatuses provided in a cabin of an aircraft include: lighting apparatuses provided at a floor surface of an aisle at prescribed intervals; lighting apparatuses that locally illuminate passenger seats for reading or the like; and lighting apparatuses that illuminate a ceiling above the aisle. Among these lighting apparatuses, the brightness in the cabin is mainly controlled by the lighting apparatuses that illuminate the ceiling above the aisle.
In recent years, for improvement of fuel efficiency of aircraft, not only the body of the aircraft but also various apparatuses installed in the cabin of the aircraft are required to be reduced in weight. For this purpose, a lighting apparatus for use in the cabin of an aircraft, which adopts LEDs as light sources, has been known (refer to Japanese Unexamined Patent Application Publication No. 2005-537613, for example). In particular, many lighting apparatuses for illuminating the ceiling above the aisle are provided over the entire length of the cabin, and therefore, using compact and lightweight LEDs as light sources of each lighting apparatus contributes to a reduction in the total weight of the aircraft.
FIG. 5 is a diagram showing an example of lighting systems using this kind of the lighting apparatuses. In FIG. 5, a lighting system 10 is used for illuminating a ceiling C above an aisle P in a cabin of an aircraft AP, and has lighting apparatuses 20 and 30 provided in two rows above and along one side and the other side of the aisle P, respectively. The lighting apparatuses 20 and 30 are mounted to upper ends of overhead storage bins 40 and 50 above a seat S, respectively, so as to be hidden from passengers sitting in the seat S. Light outputted from the lighting apparatuses 20 and 30 (indicated by arrowed broken lines) is emitted to the ceiling C and also to an upper part of the storage bins 40 and 50.